Indoor Location Research For Mobile Object Based On RFID

RFID(Radio Frequency Identification) technology as one of the key technologies of Internet of Things, increasingly used in the social production and social life, it is an automatic identification technology that exchange between a reader and an electronic tag to achieve its non-contact, distance and multiple targets. With the rapid development of RFID technology, RFID-based indoor location technology has become a hot research content. Product location and location applications of moving objects and people in large-scale logistics center can effectively improve work efficiency and reduce operating costs.This thesis presents a set of forklift location system in the logistics warehousing center which can effectively improve its management efficiency. This thesis describes the principles and components of RFID technology, and then analyzed a variety of RFID location technology including RSSI-based location method which has a strong anti-interference ability and low hardware requirements. Therefore, this thesis designed a location system of hexagon tags layout based on the regional location and RSSI-based location method.This thesis analyzes the internal structure and environmental characteristics in the logistics warehousing centers, and learns the layout in the base stations of cellular mobile communication systems, and attaches the tags to the ground surface in the shape of hexagon, placing an active tag in the center surrounded by six passive tags, forming a six equilateral triangle structure. When forklift equipped with the reader enter into the cell area, the reader first detects the active tags to precede the regional location, and then detect the largest power passive tags to precede three-point location. For the cell boundary, this thesis proposes the method of four-point location. Based on the improved triangle centroid localization algorithm, it weights positioning point and derives an equilateral triangle, three-point positioning formula. Through theoretical analysis and drawing contrasts the effect of the layout an equilateral triangle and rectangular tags layout on the location accuracy, the analysis shows the layout of an equilateral triangle has a higher location accuracy and robustness.Finally, By means of Matlab software, this thesis simulates the cellular forklift location system, and renders the location performance curve based on the simulation data obtained. To make the conclusions universal, it fixes location simulation by changing the signal noise ratio(SNR) of the system, and gets the accuracy position of the system at different SNR, and compares with the existing rectangular tags layout location method. The simulation results show that the design of location method has better positioning accuracy and robustness, when the SNR is 50 dB cellular positioning error less than 0.25 m is close to 90%.